Automatic telephone system



July 1 v1924.

ATTRNEY 2 Sheena-snee: 1

INVENTOR WNFRED T POWELL BY A9.

W. T. POWELL AUTOMATIC TELEPHONE SYSTEM i mm mi v July 1 1924. I

W. T. POWELL AUTOMATIC TELEPHONE SYST Filed May 24 1.921 2 Sheets-Sheet 2 INVENTOR wmFREDT. POWELL ATTORNEY Patented July l, 1924.

UITE STATES PATENTy 'WINFRED T. POWELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING- COMPANY, OF ROCHESTER, NEW YORK, A

CORPORATION OF NEW YORK.

AUTOMATIC 'I'ELEP-IOII'E SYSTEM..

Application filed May 24, 1921. Serial No. 472,088.

To all whom t may concer/n,

Be it known that I, WINFREDT. POWELL, a citizen of the United States, residingat Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description. i

This invention relates to telephone systems and more particularly to telephone systems employing automatic switches in establishing telephone connections.

In former telephone systems where primary line finding switches have been used it is possible for the primary line finder switch toconnect only one telephone line to an idle trunk. I'n accordance with the present invention it is proposed to simultaneously extend two or more telephone lines to idle trunks through a single line iinder switch.

It is further proposed to use a single line relay and a single cut olf relay for the use of a pair of telephone lines.

Other features of the invention will appear from the detailed description and appended claims.

The drawings with Fig. .2 placed at the right of Fig. 1 diagrammatically represent so much of a telephone system as is necessary for a clear understanding of the present invention. At the left of F ig. 1 there vare represented two subscriber substations and telephone lines connecting these substations with the main exchange. At the left of the dotted line of this figure, there appears the controlling circuits and the brushes of a primary line finder switch. At.

the right hand of this dotted line and at the left of the dotted line of Fig. 2 there is represented the controlling circuits of a. secondary finder switch. At the right of the dotted line of Fig. 2 there is represented a connector switch and a called substation.

The line finder switch of this disclosure may be of any well known type of unidirectional switch, such as that disclosed in the patentto Clement. 1,107,153 patented August 11, 1914. The numerical switches of this disclosure may be similar to that disclosed in the patent to Keith et al. #815,- 176 issued March 13, 1906.

In accordance with one arrangement of the present system the subscribers lines may be arranged in groups of twenty lines which terminate in the terminals of ten-point primary iinder switches. Each such switch is provided with twosets of brushes which simultaneously engage the terminals of two lines and each group of lines and primary finder switches are provided with a pair of primary trunks which terminate in the terminals of a forty point secondary finder switch. In this arrangement one hundred lines will be arranged in groups of twenty lines` and will have access to forty primary trunks terminating in the terminals of secondary finder switches. VThese secondary finders through their secondary trunks eX- tend these one hundred lines to any one of a group of ten connector switches. An allotter in the form of an extended starter wire arrangement is provided for each group of primary iinders and for each group of secondary Enders to allot these switches for use. It will be understood that the grouping arrangement and the percentage of trunking may be widely varied in accordance with traiiic requirements without departing from the spirit of the present invention. l

It is believed that the invention will best be understood by describing the method of establishing a telephone connection from a calling substation such as A to a. called substation such as that represented at C. When the calling subscriber at A removes his receiver from its switch hook a circuit is closed for operating the line relay 5, eX- tending from grounded battery, right hand winding of this relay, uppermost armature and back contacts of the cut off relay 6, over the upper side of the calling line through the substation circuits in series and over the lower side of the calling line, back mary line finder switch herein shown and when it is thus operated it attracts its armatures and an operating circuit is thereby completed for the motor magnet 10 of the primary line finder switch. This circuit is traceable from grounded battery, winding, baci; contact and armature of the motor magnet 10, inner armature and front con" Vtact of relay 9, back cont-act and middle armature of relay 8, test brush 11 or the iinder switch, test terminal such as 7 of noncalling lines, through the back Contact and armature of line relays similar to 5 to ground. Under the control oit similar circuits the motor magnet 10 advances its brushes 11 to 18 inclusive until the test relay 8, however, is short circuited as long as the test brush 11 encounters test terminals having ground potential such as characterizes non-calling lines. llllhen, however, the calling line is located the mentioned short circuit is removed and the relay 8 is operated in the circuit just described. As soon as the relay 8 is operated, it closes an actuating circuit for the cut oil relay 6 completed from grounded battery, winding of this relay, finder brush 18, uppermost armature and front contact ot relay 8, outer front Contact and armature of relay 9 to ground. Relay 6 on operating disconnects line relay 5 from the control of either of its associated calling` lines such as A. and B. Line relay 5 then deenergizes and removes the calling condition from test terminal 7, likewise the '.icoming test terminals ot the lines A and B are extended to the brushes 12 and 1'? 5 also when relay 8 is operated it closes an actuating circuit for the relay 2O extending from grounded battery, resistance, contact 21 and armature of relay 8, winding of relay 20, lower back contact and armature of relay 22, over the upper side 88 of the primary trunk circuit, finder brush 17 and both sides ol the calling line and substation circuits in series, the lower side 84 ot the primary trunk, upper back contact and armature of relay 22, to ground at the outermost front contact of relay 9.

1With the relay 2O operated, a substitute energizing circuit for relay 8 is closed 'from grounded battery, winding, back Contact and armature ofthe motor magnet 10, conductor 19, winding ot relay 8, contact 23 and armature ot relay 20 to ground; also at contact 24 and upper armature of relay 2O a circuit is closed from ground over the starting conductor 25 lower back Contact and armature of relay 26, winding orL relay 27 to grounded battery. Relay 2T closes an operating circuit tor the motor 28 ot t-he allotted secondary line rlinder trom grounded battery winding, armature and back contact of motor` magnet 28, upper armature and back contact or relay 26, u apermost armature and front o1 relay 2?, secondary linder brush 34A, back Contact and armature ot' relays similar to 29 and 2() to ground. Under the control oli' such circuits the motor magnet 28 ad vances the brushes 8O to 87 inclusive until the t brush 811 encounters the trunk circuit that has been extended to the calling line by the primary line finder switch: this trunk will be indicated by the absence o' ground potential due to the energization of either relays 20 or 29. 1t will be understood that an operating circuit was closed for relay 26 as soon as the starting relay 27 had operated, its circuit being closed from grounded battery, winding of the motor magnet 28, its armature and back contact, winding of relay 26, inner' armature and 'front contact of relay 27 to ground. Re lay 26, however, is shortcircuited by ground potential applied through test brush 84 until the selected primary trunk is located at which time the mentioned short circuit is no longer completed and rrelay 26 is operated to interrupt t-he operating circuit of 2'?. lll/lith relay 26 operated, a circuit isclosed oriactuating marginal relay 88 extending from grounded battery, winding, armature and baclr contact of the motor magnet 28 upper armature and front Contact ot relay 26, winding of relay 88 its continuity spring and back contact, lowermost front contact and armature or" relay 26, finder brush 80, front contact and armature of relay 2O to ground. rllhe relay 88 when operated. closes a locking circuit Jfor itself through its inner armature and continuity spring to ground. The relay 88 is marginal so that it will not energize in series with relay 89 and it will be noted that relay 89 is short circuited by the mentioned operating circuit ol? relay 38 so that relays 88 and 89 will not be simultaneously operated thus assuring that only one subscribers line will be extended to the trunk circuit terminating in the numerical switch of Fig. 2. llt the contact l0 and armature ol' relay 88, ground potential is applied over finder brush and primary finder brush 17, and through the innermost front contact and armature ot relay 6 to apply a guarding potential to conductor #l1 which is connected to test terminals of the calling line A t the various connectors through which it be reached as a ailing line. At contacts l2 and 4.1.8 of relay 88, the calling` line is extended through both windings in series or' the impulse relay 14 to grounded battery. Impulse relay 44 is thereby energized and at its armature and front contact closes an operating circuit tor the slow releasing relay 45. This relay at its outer armature and front contact closes the holding conductor 46 which maintains the holdingv relay 26 operated.

The apparatus is now in condition to receive the directive impulses trom the impulse transmitter at the calling substation. For purposes otthis description it has been assumed that the secondary trunlr terminates in a connector switch but it will be understood that it it is desired-to employ the present invention in a relatively large system numerical switches such as iirst and second selectors will be employed to extend the calling line to a connector switch through which the called line can be reached.

The calling subscriber at A thereupon operates his impulse transmitter a series ot impulses correspondingto the tens digit of the wanted number. In response to cach ol these impulses the impulse relay 44 retracts its armature and closes a circuit from ground through the inner armature and front contact of relay 45, winding ot the change-over relay 47, side switch wiper 4S lin its first position, primary motor magnet 49 to grounded battery. Relay 47 is energized to ycause the operation ot the escape magnet and since relay 47 does not deenergize during a series et impulse, the escape magnet is held operated. Under the control ot this magnet the motor magnet 49 advances itsrbrushes 50, 5l, and 52 in their primary movement to select a group ot lines through which the called line may be reached. rt the close ot this series ot impulses the impulse relay 44 holds its armature attracted tor a relatively long period Y so that the slow releasing change-over ren lay 4'? deenergizes and opens the operat-l ing circuit for the escape magnet 53, whereupon this magnet advances its wipers into their second position. rPhe subscriber at A now dials the units series of impulses and the impulse relay 44 now vibrates its armature to close an operating circuit for the secondary motor magnet 59, trom grounded battery, winding ot this magnet, back contact and armature ot relayT 55, side switch vwiper 48 in its second position, winding ot the change-over relay 47, inner front contact and armature oirelay 45, back contact and armature of relay 44 to ground. Relay 4i' when actuated, closes an actuating circuit for the escape magnet 53, traceable from ,grounded battery, resistance, winding ot this magnet, continuity spring and arma ture of change-over relay 47 to ground. Since the change-over relay 47 is slow-releasing, it holds the escape magnet 53 operated during the units series ot impulses.

In response to each retraction ot the armature ot impulse relay 44, the described operating circuit or' the secondary motor magnet 59 is completed and this magnet advances the brushes oi' the connector switch 'in their secondary direction to select the This Y Sti moves the side switch Wipers into their f third position. Here the escape magnet 53 is maintained energized through side switch wiper 63, to ground at the back contact and armature of release magnet 64.

In this position ringing current is applied to the wanted line in a signalling circuit completed from ground, ringing generator 56, lamp 57, side switch wiper 58, connector brush 5l, through the lower side of the wanted line and the signal of the wanted station over the upper side ot the wantedY line, connector brush 50, side switch wiper 89 in its third position, winding of the trip relay 60 to grounded battery. Ringing current is applied over this circuit until the called party responds at which time the re lay 60 is operated and at its upper armature and contact short circuits the escape magnet 53 causing it to deenergize and advance its side switch wipers into their fourth or talking position.

The talking current is supplied to the calling party through the windings of impulse relay 44, while talking current is supplied to the called party through the windings ot' impedance coil (il.

In the event that the wanted line is busy when it is tested by the test brush 52 ol the connector, as soon as the change-over relay 47 deenergizes, the escape magnet 53 will be maintained energized in a. circuit closed from grounded battery, resistance, winding of this magnet, continuity spring and back contact oit relay 47, winding ot the test relay 55, its continuityr spring and back contact, side wiper 62 in its second position, test brush 52 and test terminal ot the called line and through the multiple test terminal and test brush similar to 52 at the connector that has already seized the called line through a side switch wiper similar to 62 associated with this connector switch in its i'ourth position to ground. TJnder the controlv of this circuit the escape magnet 53 is maintained operated and the test relay 554 is actuated to close an operating circuit for itself through its continuity spring and armature, otf normal contacts 65 to ground.

iso

With the escape magnet 53 held operated the side switch does not advance trom its second position, so that the busy called party is not signalled. filso with the 'test relay 55 locked operated busy tone current B Z is applied through t ie lowerinost armature and front contact of this relay to the calling line to i'orm the calling subscriber that the wanted line is busy.

When the calling subscriber at A terminates a call, he replaces his receiver on its switch hook. 'lhe impulse relay del deenergizes and thereby opens the operating circuit ior the slot.y releasing holding relay 45. fit the outer armature and bach con tact of this relay r the release magnet A d from grounded battery. liiinding ot this magnet oil normal contacts baci; contact and armature ot relay to ground. rihe re.- lease magnet thereby releases the coiinector switch as well its side switch wipers into their normal position. the outer armature and' liront contact or re 45 the holding conductor o is ooe-ned per-- mitting the holding` relay to cie-energize. This relay opens the cli-J' of marginal relay 38 to disconnect the impulse relay from the` secondary finder brushes and 3T. it contact` l0 and armature ci relay 38 the holding conductor 68 which has been maintaining the holding' relay operated is interrupted and this relay retracts its armatures.

ln the event that a subscriber at station B originates a call when the associated line from substation ifi is not calling, then thV line relay 5 will energize the starting relay 9 which causes the motor magnet l0 to advance the brushes et the primary line finder switch to locate the calling line in theI inanner already oescnhed, halben the calling line leading to substation B is located, relay 8 will be operated and this in li-urn will cause the operation ct relay 29. Relay 29 when operated causes tle cniation or starting relay 27 which causes the niotor inagnet 28 to advance the brushes of the secondm ary line hinder switch to hunt i'ior the primary tiuiilr that has been connected to the calling line. lli/Then this primary triinh is located the operation oit the motor magi 28 will be stopped and relay will be operated to ei'llect the operation oi' the relay 39. Relay 39 on attracting its armatures eX- tends the talking brushes 8l and oil "he secondary line linder switch to the connector switch. ml

iiiis relay at its innermost armature and iront contact also closes an operating circuit for relay TO which serves as a holding relay tor thc primary line iinder switch by reason ot its completing a holding circuit tor the relay 8. This circuit is traceable from grounded battery winding, back contact and armature of magnet inserer/i l and conductor 19, winding of relay 8, uppermost liront contact and armature of y ./0 upper iront contacts and armature ot ielay 8 to ground. The release ot this portion ot the connection will take place in the manner already described.

Let it be assumed that the subscriber at substation B 'originates a call at the time when the subscriber at substation A is establshing or maintaining the connection. Under this assumption the cut off relay 6 ane relay 8 will be operated. Therefore, when the subscriber at B removes his receiver from its switch hook an operating circuit is closed 'for the relay 29 from grounded battery, resistance, innermost .lower armature and front contact of relay 8, winding` ot' relay 29, inner back Contact and armature ot relay 70, through finder brush la, over the upper side of the calling` line and substation circuits in series, over the lower side oi the calling line, finder brush i3, uppermost back contact and armature of relay "ZO, inner iront contact and armature oit relay 8 to ground. With relay 29 operated a secondary finder start-ing circuit closed troni ground at the lower armature. and iront Contact of relay 29 over the conductor 25, but in this instance the starting circuit is entended through the inner armature and liront contact of relay 26, loner armature and back contact of relay 2"? to tne out wire leading to the next idle secondary line Ender. This linder switch will then operate in the same manner as e described secondary line finder but this case will extend the calling line from substation B to an idle connector switch (not shown).

lf the subscriber at A. disestablishes the connection before the subscriber at B desires to terminate his conversation this last mentioned connection will still be maintained, for the. holding relay :8 will still be in. tained operated in a holding circuit completed at the uppermost front Contact and armature of relay 70.

liet it be assumed that call is extended to the substation i through the test brush such as 52 of the connector which has been seized by the calling line and is in engagement with the multiple test terminal of substation fi. Ground potential is extended through a side switch wiper such as 62 in its third or fourth position, a test brush suchv 52 at the mentioned connector, tl'irough conductor 4l of Fig. l innermost armature and back contact of relay 6, left hand winding of line relay to grounded battery. The line. relay 5 is thus operated and closes the starter wire to cause the motor magnet l() to operate. This magnet advances the brushes ll to 18 inclusive of the primary line finder switch until the terminals of the called line are located.

i, is stopped, at which time, relay 8 is operated in a circuit already described and thereby effects the operation of the cut ott relay 6. With cut oli relay actuated, the

holding relay 22 is operated in a circuit completed from grounded battery, winding of this relay conductor 68, linder brush 17, innermost front contact and armature or' relay 6 and conductor 4l to ground through the side switch wiper similar to 62 at the connector that has seized the calling line. It will be understood that in this instan-c relay 22 operates before the subscriber at A removes his receiver from its switch hook and thereby prevents the operation of relay 20. This insures that a secondary line iinder switch will not be operated to seize the primary trunk circuit just extended to the called line.

It will be understood that this disclosure is merely typical or the present invention and that there may be many variations in the same within the scope of the appended claims without departing from the spirit oit this present invention.

il/That is claimed is:--

l. In a telephone'system, pairs of telephone lines, a plurality of non-numerical switches, a pair of trunks for each ot said switches, means for allotting non-numerical switches tor use, means for simultaneously extending the trunks ot a non-numerical switch to a pair of lines.

2. In a telephone system, a pair oftelephone lines, a single line relay and a single cut ofl relay for said pair of lines, a nonnumerical switch, trunks individual to said switch, operating means tor said switch controlled by said line relay, means tor operating said line relay controlled over either of said lines to initiate the actuation ot' said operating means and means responsive to the connection of said trunks to the said pair of lines for operating said cut oil relay. A 3. In a telephone system, a pair of telephone lines, pairs of trunk circuits, a pluralitv of non-numerical switches any one of which will serve to connect said telephone lines to a pair of trunk circuits and means for allotting switches for use.

4. In a telephone system, pairs of incoming circuits, pairs of out-going circuits, nonnuinerical switches any one of which is effective to connect said pair of incoming circuits to a pair of outgoing circuits, means for allotting non-numerical switches for use and means responsive to the initiation of ya call over either of said incoming circuits to extend said circuits to a pair of out-going circuits through an allotted non-numerical switch.

5. ln a telephone system, a pair of incoming circuits, a relay arranged to be operated over either of said incoming circuits on the initiation ci a call thereover, pairs of out-going circuits, switching mechanisms each allot- `ted one of which is ei'lective on operation of said relay to -connect said incoming circuits to a pair of idle out-going circuits, means for allotting idle switching mechanisms for use and means responsive to the connection of said incoming circuits to said oiit-going circuits or removing said relay from the control o the incoming circuits.

6. In a telephone system, pairs of incoming circuits, non-numerical switches, a pair of out-going circuits for each non-numerical switch, means for alloting idle switches for use, a relay for said incoming circuits arranged to be energzed over the two sides ot either of said incoming circuits in series, means responsive to the operation of said relay for causing the allotted non-numerical switch to extend its pair of out-going circuits to said incoming circuits and means for releasing this established connection.

7. In a telephone system, a plurality of non-numerical switches each switch being provided with sets of brushes and fixed terminals arranged to be engaged by said brushes, incoming circuits terminating in said fixed terminals, out-going circuits terminating in said sets of brushes, means for extending said incoming circuits to said outgoii'ig circuits through one of said switches, trunk circuits and means for extending said outgoing circuits to said trunk circuits.

8. In a telephone system, a plurality or' non-numerical switches each ot which is provided with sets of brushes and fixed terminals arranged to be engaged by said brushes, incoming circuits terminating in the fixed terminals of said switches, out-going circuitspfor each set of brushes, means for allotting said switches for use and means responsive to the initiation of a call over any ot' said incoming circuits for extending said incoming circuits to out-going circuits through an allotted switch, trunk circuits and means for connecting outgoing circuits to said trunk circuits. i

9. In a telephone system, a plurality of primary non-numerical switches, incoming circuits and out-going circuits terminating in said switches, means for allotting idle primary switches for use, means for extending incoming circuits simultaneously to outgoing circuits through an allotted primary switch, secondary non-numerical switches in which said out-going circuits terminate, trunk circuits, means for allotting secondary switches for use and means including allotted secondary non-numerical switches for extending out-going circuits to idle trunk circuits.

10. In a telephone system, a pair of incoming circuits, pairs of outgoing circuits, means for allotting out-going circuits for use, means for connectinga pair of incoming circuits to a peir of allotted out-going circuits When a call is initiated over one of said inconiingeircuits, trunk circuits each provided Witli a pair of branches accessible to either one of the allotted pairofout-going circuits and means responsive to tliejconnection of oneof said outfgoing circuits to one of said branches of said trunk circuit for rendering the other branch inaccessible to M) tlie other out-going circuit of the pair.

In Witness Whereohl hereunto Subscribe my name this 23rd dayiof May, A. D. 1921.

' WINFRED T. POELL. 

